The present invention relates to radiation producing apparatus in general, and more particularly to improvements in apparatus which can be used for tanning of human skin and/or for therapeutical purposes. Still more particularly, the invention relates to apparatus (popularly known as sunlamps) which are designed to produce and orient infrared and/or ultraviolet radiation. Such apparatus comprise one or more radiation sources (e.g., ultraviolet lamps), one or more reflectors and means (including or constituting the reflector or reflectors) which defines one or more exit openings for radiation.
Sunlamps are often classified according to the dimensions of the radiation field. Thus, a table model is normally designed for directing radiation against selected areas (especially the face and the upper part of the torso) of the human body, and a floor, wall or ceiling model is normally (but not invariably) designed to direct radiation against the entire body. Sunlamps of the type capable of producing radiation fields which are large enough to effect simultaneous tanning of all parts of a human body are sometimes called solaria. As a rule, a person who is about to acquire artificial tan by using a table model must be positioned at a distance of 60 to 100 centimeters from the exit opening of the sunlamp. In a solarium, whose radiation source or sources are normally installed at a level above a bunk, couch, cot or bed, the prescribed distance from the exit opening is in the range of 120 to 200 centimeters. A table model frequently comprises a single radiation source, and a solarium comprises several (often three) radiation sources, especially in the form of high-pressure discharge lamps for ultraviolet radiation. The output of radiation sources for table models is 100 to 150 watts, 150 to 200 watts for relatively small solaria (normally for use in private homes), and 350 to 500 watts for use in giant solaria.
A sunlamp is used primarily to produce a sun-tanning effect. However, before a conventional lamp produces a discernible tanning effect, ultraviolet radiation causes many other (mostly undesirable biological effects, such as reddening of the skin (sunburn) which entails flaking and hardening of the skin. Since the minimum dosage of ultraviolet radiation which produces sunburn is reached within minutes (especially if the density of the radiation field in the region of exposed skin is high), i.e., well before the skin begins to exhibit even a slight trace of tanning, the exposure of skin to ultraviolet radiation must be repeated again and again whereby the duration of exposure normally increases from treatment to treatment. However, even the just described mode of using a sunlamp cannot produce a deep tan such as is acquired by prolonged exposure to sun rays.